Top coating polyurethane with marine varnish on exterior doors.

I have been a professional on site woodwork refinisher for 33 years. It drives me nuts to see people buying new exterior front doors and three years later the finish is turning white and peeling. There is a simple and cost effective method home owners can do.

Sand your door lightly with #220 sand paper. Tack it down with a rag soaked with paint thinner and a little varnish to make a tack cloth. Buy two quarts of Marine varnish one gloss and the other the sheen of your choice.

Take a bristle or preferable an ox hair brush, and brush the varnish on brushing in one direction going from dry to wet. You have to lift and back brush only, because marine varnish will dry so fast you will have a mark every where you set your brush down. Let it dry 24 hours and repeat. You can choose gloss semi gloss or satin.

This method works great,and will last for years. My clients look concerned when they pay me saying “how long will this last”. They are overjoyed when I send them a reminder message after four or five years that it’s time to re-coat. Home owners can do this themselves. It is just real important to use a true marine varnish. I use McCloskey’s Man-Of-War, but there are other company’s that make it. You just have to make sure it is a true marine or spar varnish. Submit questions or success or failure stories or photos.

I strictly refinish new finish front doors in Cincinnati Ohio. I know that marine varnish is better. I have gone back and recoated front doors 8 years after new finishing or refinishing and sanded and done one top coat and they look like brand new. Valspar makes McClusky’s Man-O-War now. They reformulated it 4-5 years ago. It is not quite as durable as it was before but it still has any other product I have tried beat. I have 39 years in the on site front door finishing refinishing trade.

I am getting ready to finish an exterior door with stain followed by polyurethane. I purchased an oil-based exterior/interior polyurethane, but will this give the door the same protection as a spar varnish?

The gloss is the first coat and is used for sealing purposes. I think you could use the same sheen as the final finish for this purpose, example-satin used for both coats. The advantage to using gloss for the first (seal) coat is; a little better penetration than satin and the final coat will slide on a little easier.

It’s up to you if you want to use 2 different sheens. Personally, I use the same sheen for both coats.

The gloss is also totally clear.If you use 4-5 coats of satin you will have a bit of a cloudy look.They add silica sand to flatten gloss to active satin.That is why I use gloss for the base coats.I am finishing a new cherry door for a client right now.They are very conservative.I used 4 coats of gloss and the final coat they chose satin!

I’m a little confused. You say to buy one quart of gloss varnish and one quart of your own preference – gloss, semi-gloss, or satin. But you don’t say how the different “quarts” are used. – Do you mix them together? I don’t understand.

I buy gallons of GLOSS marine varnish to put the first 3-4 coats of varnish on my doors.I do this because the gloss is totally clear.I use satin for the final coat if the client wants satin.They make all varnish in huge quantities in gloss then add cilia sand in increasing proportions to flatten it down to semi gloss satin or flat.The cilia sand makes a cloudy look that I don’t like.If the client want satin I use satin for the final coat.I use cone filters to strain the base coat and ladies nylons to strain the final.Use a bristle brush that has NEVER been used for paint because if there is old paint in the heel you will ghet paint specks in the fresh varnish.ALLWAYS USE MARINE/SPAR VARNISH EXTERIOR!!!

I recently bought exterior door Douglas Fur and had it sanded and then stained Mahagony by professional, polyurathaned it. The sanding was unfortunately bad and the 3 coats of polyurethane (not Marine) were applied. The door looks dry, raw completely flat and without life. It’s very upsetting, we would like your advice using on the door marine varnish and sand the door lightly before the application. What are your thoughts? Thank u so much, Regards Anna Wachel

Use oil base color putty, available in many different colors and it can be intermixed for custom colors. This will remain soft and a little flexible for a while. But, in the end you have to refill the cracks from time to time.

What would I need to use to fill gaps in tongue and grove caused by expansion and contraction due to heat and cold? We live in Colorado where we can have both extremes in one day. I’d love to refinish my own door, but need to address this issue first. Thanks for the great advice!

Sometimes I have cracks I can’t get to fill.After I finish I sometimes fill cracks with clear cylicone chalk.This will prevent water from collecting in the crack.And it is clear so you will never see it!

This is excellent advice based on my home owner experience. This article is written for painting professionals. So it is little difficult to follow. A link to YouTube video will solve the problem for DIY guys. Nevertheless the advice is top notch and therefore I gave 5 stars.

If it turned white it got contaminated with water.You can use spar varnish oven OIL BASSED paint.Try a small inconspicuous space.If the varnish separates and won’t flatten out it is water based point and marine varnish won’t stick to it.There are water based ploys but my understanding is they won’t hold up outside!!!

I have seen people use some type on clear coat on exterior stone. I have not. Varnish is VERY sticky. It sticks to my hands so bad I have to clean my hands periodically during the work day. I would try a small sample and leave it on for a couple of weeks before I would try it!

Can the Spar varnish be used over a stained wooden door, under a glass storm door with Western exposure? I think the painted surface has bubbled due to heat. I am having the door stripped and starting over. Help!

Question: I just stripped/sanded/stained (using MinWax wood finish penetrating stain) and put a couple coats of an exterior polyurethane over the “side lights” which are on the right & left of my front door (haven’t done door yet). Can I put the McClusky’s Man-O-War over the polyurethane? Or do I need to restrip and do this over? (NOTE: When I was doing the “light sanding” between polyurethane coats, I noticed that some of the polyurethane was coming up — not just sanding off)…. I live on CO and not sure if current weather (hot but humid day) had something to do with the pealing up during sanding. Wish I had seen this post earlier…

Hello, Is it ok to leave the doors on the hinges or is it best to remove them to apply the varnish? I have heavy 8′ double doors that would be tough to remove. How much varnish would typically be needed for 4 coats to the double doors with transoms and with sidelites? Lastly, should the stain be reapplied before varnish goes on? Thanks in advance!

Yes it is, actually it is the only way to apply the varnish to front doors and have them closed at the end of the day. Make sure to remove the weather stripping so the door doesn’t stick.

You will need a couple quarts. Since the doors will be up your coats will be thin and watch for runs, runs can happen for about an hour after application. Plus make sure all staining is finished before applying any varnish.

I need some advice. My front porch is being renovated. We are wrapping my posts in cedar and putting in a new front door. Can I use PPG Timeless semi-transparent stain and sealer in one for the cedar columns and door and then finish with Man O War marine spar varnish? Just wondering what would be best.

Yes this will work well. Make sure to allow ample dry time before applying the varnish, a couple days with good warm weather should be OK. Once the varnish is applied and dry it will seal off the surface not allowing degassing, the PPG stain will need a little time to stop degassing and cure before being sealed.

I bought a mahogany door for my front entrance. The painter applied one coat of McCloskey Man-of-War but no stain. Now the door looks like it has stripes. Not at all what I was expecting. It looks more like hickory than mahogany. I can’t get a straight answer from the manufacturer or the painter. Is it a problem with the door or the fact that we used marine varnish withou staining it first?

Without seeing the door it hard to say what is the problem. But, this could be a product of the varnish alone. With 1 coat it is possible you are seeing a combo of brush marks and unequal absorption of the varnish.

I am building hanging plant stands that will be outside. I wanted to avoid using pressure treated wood and couldn’t readily get cedar so I went with douglas fir with the intention of using Hellman’s Spar Urethane that I already had to seal them. I used an exterior paint and primer in white and the Spar turned them yellow in spots. Will the oil marine varnish do the same or do I need to use something with a water base and will that hold up outside. Also what about for other colors….black, turquoise, and regular stains…would the Spar be okay for those. I have a whole gallon I’d like not to waste. Thanks, KB

All oil based clear finishes have a amber color and this will change the color of white paint. Used over other darker colors will be less noticeable. The Hellman Spar you have is well suited and recommended over stains.

Using a water based clear coat will eliminate the yellow but might not hold up as well.

What would be the best clear or satin top coat for a metal exterior garage door that I have painted with an exterior flat paint and then did a faux wood with Old Masters Gel Stain? the garage doors face south so exposed to sun and heat in Southern California. Need something with UV protection and durability. Water based Spar Urethane or Marine Spar urethane. What brand is the best for what I’m doing? HELP!!!

Great thread. Sure wish I understood “Take a bristle or preferable an ox hair brush, and brush the varnish on brushing in one direction going from dry to wet. You have to lift and back brush only, because marine varnish will dry so fast you will have a mark every where you set your brush down.” I guess I’m so dumb I need a video or a few more words;-)

I appreciate your comments about using marine spar varnish. I have made porch columns out of cedar and would like to try this out. Do you have any suggestions regarding stain or sealants that can be used to enhance the grain? Minwax and Varthane stains are recommended only for interior applications.

The interior stains will work fine as long as you put a good exterior clear coat over them, such as an exterior varnish. If you want even more protection you could use an exterior transparent wood stain, oil based, for 1 or 2 coats then put the varnish over that. I don’t think that is needed in more cases.

I have a Therma tru fiberglass door I am using gel, oil based stain on. The instructions say to use a water based polyurethane after. Is Man of War water based? If so, can it be used on a fiberglass door? Any recommendations are appreciated. I have used Therma Tru products in the past but find them to be limited in colors and very expensive.

Man o War is a varnish, oil based. But, it can be used on fiberglass with no problems and will hold up well. For additional stain color choices try Old Masters gel stains, easy to work with and perfect for fiberglass doors.

We have mahogany doors that were sealed with 5 coats of aliphatic urethane (AU). Do you know of any reason why I should NOT lightly sand and apply a UV Spar varnish periodically to maintain and keep the doors looking new? I’m unsure if the varnish will cause issues with the AU and I don’t want to ruin the doors. Thanks for your thread!

Using a good spar varnish if fine. The varnish is needed only if you think the current finish is too thin or failing. With 5 coats of urethane a periodic washing to remove dust and oxidized finish is all that is needed, at least for the time being.

Yes you can but use a small tip and turn down the pressure. A 310 or 311 tip with 2000psi or less will work, adjust the pressure for a good fan. And move quick when spraying, thin coats are way better than thick ones.

That sounds like a great idea. I REALLY need some help from an expert! I have never done any of this before but I have been researching for literally 3 days straight. I need some guidance. I REALLY want to use the spars varnish on the floors we are redoing! Nothing else has the same shine, but I thought maybe putting down a couple of thick coats of some kind of oil based poly first might make it more even and durable? Will that work? I really need some advice! Thanks!! 😊

McCloskey’s Man-Of-War spar varnish, as mentioned in this article, is an excellent finish but not for floors. Spar varnish is too flexible to be walked on. I don’t think putting it over polyurethane would make a difference for durability, although spar varnish can be applied over poly and stick fine.

I have seen some very shiny floors that used a floor polyurethane. I would go to a wood floor supplier and talk to them about a finish that has the sheen your looking for.

I am finishing a fiberglass door and have put on a coat of marine varnish in gloss over gel stain, but I cannot find satin marine varnish and that is the sheen I want. Can I apply a satin spar urethane (like helmsman) over the marine gloss to knock down the shine? Thanks in advance this is super helpful!

Wait 18-24 hours, or overnight before recoating. Don’t want to reactivate the previous coat of varnish. A light sanding with a fine sanding sponge or paper, 220-280 grit, is desirable. Make sure to remove all dust with a tack cloth or clean damp rag. This simply helps give a nice smooth surface and helps with adhesion of the next coat.